Process for regenerating spent internal-combustion engine lubricating oils



Patented Aug. 3, 1948 Z. 'FFICE PROCESS FOR REGENERATENG SPENT IN-.

TERNAL-COMBUSTIQN' ENGINE LUBRI- CATIN G OILS Albert Schaafsma, Amsterdam, Netherlands, as-

signor to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application March 11, 1946, Serial In the Netherlands March 21,

'.Qlaims. (Cl. 196-16) It is known to regenerate spent lubricating oils, transformer oils, insulating oils and the like, in order to make them fit again for use.

The regeneration followed: mainly depends on the extent to which the, oils are polluted and the nature of the pollutions. In. this connection the respective oils may be divided. into three categories, viz.:

1) Oils which are littleafiected such as transformer oils, turbine oils and the like, which often are only polluted by water and/or small quantities ofsolid substances. These oils can be regenerated ina simple, manner .by sieving, centrifuging and, if desired, by a treatment with Ibleaching earth, for which, for instance, floridine is used.

(2) So-called industrial lubricating oils, for instance steam-engine oils and the like. These oils, if only slightly affected, can be cleaned in the manner mentioned under 1, but in the case of a more serious attack a combination of a chemical (sulphuric acid) and a physical cleaning has to be applied.

(3) Seriously afif-ected oils, in particular oils which have been used for the lubrication ofv combustion engines. The patentfapplication exclusively relates to this category of oils.

According to Biisner, Chem. Zeitung, 1935, page 921, in the treatment of these oils a distinction should be made between cleaning, improving and regenerating. By cleaning is then understood the removal of water and solid substances. Improvement is a treatment of the spent oil in which also, for instance, asphaltaceous substances, metallic soaps and suchlike substances are removed without the improved product being equal to the fresh oil, however. An equivalent product is only obtained by regeneration, which up to now has been carried out by a suitable combination of physical and chemical treatments.

In V. D. I. Zeitschrift, 1941, page 33, the following combination of treatments is given as the standardized regeneration process:

(1) ,A:mechan-ical preliminary cleaning;

(2') A treatment with sulphuric acid;

(3) Aneutralization and preliminary bleaching; (4) A distillation;

(5) ,A final bleaching and filtration.

The invention relates. to the regeneration of engine oils in thesense that regenerated oils are obtained the properties of which can be compared in'every respect with those of the fresh oil. As a matter of fact it has been found that 2 spent, seriously affected engine oils, apart from the removal, if necessary, of water, low-boiling hydrocarbon fractions and excessive qauntities of carbon, can be regenerated in one treatment by percolating them through bauxite at temperatures above 200 0., but below temperatures at which considerable cracking takes place.

By percolation through bauxite is understood the passing of the oil at the velocity desired through a thick layer of granular bauxite. It is possible to have the percolation take place at anincreased or reduced pressure.

The best results were found to be obtained at temperatures above 200 C. In the first place the yields are greater than below 200 C., whilst moreover it appeared that below 200 C. all the carbon particles did not remain behind in the bauxite; at a percolation temperature of 100 C., for instance, the oil drained off is black.

The bauxite used can be regenerated many times by a treatment with oxidizing gases at elevated temperatures, by which the organic substances deposited on the bauxite are burnt off.

By applying the process according to the invention the sulphuric acid treatment which is usual in the known regeneration processes and the subsequent neutralization are therefore eliminated, which is in many respects an advantage, especially as regards the oil losses. If the oil contains water, this should be removed preferably before the percolation, which in most cases can be done either by settling or by distillation, when also any lower-boiling hydrocarbon frac tions present can be removed at the same time. If the oil contains more than 1 per cent. of carbon, which, in general, is not the case, it is preferable to remove this carbon before the percolation, for instance by centrifuging.

A special advantage of the process according to the invention is that oils are obtained ofthe shade desired (greenish).

In principle any kind of bauxite may be used. By preference, however, bauxite is used with a low iron content, which has been found generally to be more active. No bauxite with a low iron content being available, a bauxite with a higher iron content may be treated with, for instance, hydrochloric acid, in order toreduce the iron content.

The size of grain of the bauxite may vary, for instance, from 10 to mesh, corresponding to about 0.2-1.0 mm. The bauxite may be placed in a cylindrical vessel of a diameter of 1-5 metres and rests on a perforated plate or something of a similar nature. The thickness of the 3 layer may vary, for instance, from 1 to metres. Before use the bauxite is dried and activated by heating it for some time to, for instance, about 500 C.

At the beginning of the percolation naturally more intensely refined oils are obtained than at the end. The percolation is continued as long as the average percolate still has the properties desired. It finally the oil drawn on at the bottom of the percolation column cannot be added to the total percolate, the percolation is discontinued and the regeneration of the bauxite is proceeded to.

This regeneration can take place in the same column, but the bauxite may also be put into a special apparatus for that purpose, for instance a furnace either rotating or not.

First, for instance, the oil adhering to the bauxite is recovered by steam or washing with gasoline, then the adsorbed substances are removed by burning off. If, however, the regeneration is carried out by subjecting a cohesive layer of bauxite to oxidation, the. adhering oil need not be recovered in this manner, as it has been found that on the oxidizing gas being introduced at the top this oil during the burning ofi drips from the bottom of the percolation column. It should be seen to that the temperature does not become too high, as otherwise the bauxite loses its activity. This maximum temperature lies at SOD-900 C.

Examples of practical application I. A spent engine lubricating oil which contained less than 1 per cent of carbon was percolated at various temperatures at a rate of 0.5-1 kg. of oil per kg. of bauxite per hour through granular bauxite which had been activated by heating for some time to about 500 C.

Both the results and the properties of the base oil are given in the table below:

[Percolation temperatures in C.]

4 oil obtained after the fouteenth regeneration of the bauxite.

The yield was 158 per cent by weight of percolate, calculated on bauxite. With an input of 100 per cent by weight of oil, decarbonized and distilled off, 76.9 percent of percolate was obtained (after steaming 73.8 per cent). From the bauxite 16.4 per cent. of oil was recovered, which can be percolated again, whilst the lubricating oil losses amounted to 6.7 per cent.

Base material decarbonized Steamed and distilled percolate Spec. gravity 0. 903 0. 899 Viscosity E. 50 8. 25 9. 3 V 92 91 Flashpoint closed. 130 204 Flashpoint open" 164 217 Conradson Carbon Test 1 0. 96 0. 48 Acid number 0. 41 0. 05 Saponification number 1. 3 0. 1 Colour Union 8 6 Colour Union after age 7- Yield .percent. 100 73. 8

1 After removal of the 0.9% carbon particles.

By percolation of the oil which had remained behind in the bauxite and was recovered from it the yield of 73.8 per cent, by weight is increased to 83 per cent. by weight. By a treatment of the same base material with sulphuric acid and afterwards with such quantities of lime and terrana that an equal refining loss was the result, the cleaning obtained proved to be insuiiicient in various respects. The acid number of the oil regenerated, for instance, was 0.8, the saponification number 1.0 and the colour 8.

I claim:

1. The process for regenerating spent internal combustion engine lubricating oil comprising the step of percolating said oil through a bed consisting of activated bauxite of at least one meter thickness at a temperature of about 260 C.

base oil 100 0. 200 C. 240 C. 265 C. 290 C. 310 C.

Spec. grav. at 20 C 0.893 0. 894 0.894 0.894 0.894 0.895 Viscosity Engler at 50 C 7. 8. 7 8. 5 9. l 9.1 8. 0 5. 9 Acid number 0. 3 0.05 0. 05 0. 05 0. 05 0. 05 0. 05 Saponification number: 1. 9 0. 1 0. 1 0. 1 0. 1 0. 1 0. 1 Conradson Carb. Test-.. 0. 2 0.38 0. 0. 44 0. 60 0. 56 Colour Union 8 6 5- 7- 7- 7- 8 Indiana Test:

0.1 percent by weight of sludge after hours.... 68 69 62 19 12 1 percent by weight of sludge after hours 114 108 103 60 30 Viscosity ratio after hrs 1. 26 1. 19 1.23 1. 36 1. 54 Viscosity ratio after 100 hours 1. 61 1. 61 1. 63 1. 69 l. 99 Yield percent by weight on oil 100 75 86 86 89 89 The yields mentioned in the table are the percentages of percolated oil which were obtained after treatment of the percolate with steam, owing to which the odour is improved and small quantities of cracking products are removed.

The oil remaining behind in the bauxite can for the greater part be recovered, for instance, by extraction with the aid of a solvent. This oil may be added to a following charge of oil to be percolated or it may be percolated separately.

II. A very seriously affected, spent engine lubricated oil which contained about 3 per cent of carbon was first freed from water and gasoline by distillation and thereupon the carbon content was reduced icy/centrifuging to 0.9 per cent. Then the oil was percolated at a temperature of 260 through activated granular bauxite at the velocity of 1 kg. of oil per kg. of bauxite per hour. The results given below are those of the 2. The process for regenerating spent internal combustion engine lubricating oil comprising the step of percolating said oil through a bed consisting of activated bauxite of at least one meter thickness at a temperature of from about 240 C. to about 290 C.

3. The process for regeneratin spent internal combustion engine lubricating oil comprising the step of percolating said oil through a bed consisting of activated bauxite and having substantial thickness sufiicient to regenerate said oil by said percolation alone, said percolation being carried out at temperatures of at least about 240 C., but below those at which considerable cracking occurs.

4. The process for regenerating spent internal combustion engine lubricating oil comprising the step of percolating said oil alone through an adsorbent bed of at least. one meter thickness and REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,121,518 Breth et a1 June 21, 1938 2,170,628 Breth Aug. 22, 1939 2,390,917 Breth et a1. Dec. 11, 1945 2,403,088 Laing July 2, 1946 2,419,579 Livingston Apr. 29, 1947 

